Reversible nip roller drive system

ABSTRACT

A reversible nip roller drive system for delivering an elongated band, tape, strap or the like in both a forward and reverse direction as required, with one nip roller of each set of paired nip rollers being translatable between an open and closed position, the nip rollers being connected to associated nip pulleys. The nip pulleys are driven by an interconnected drive belt, preferably toothed, mounted on pulleys or sheaves. The system has a drive pulley, two pairs of nip pulleys connected to the nip rollers, each pair having a fixed pulley and a linearly translatable pulley, and a linearly translatable idler pulley. The drive pulley and the two nip pulleys on one side of the band are stationary or fixed in place, whereas the idler pulley and the opposing nip pulleys are simultaneously linearly translatable relative to the other pulleys, the idler pulley being disposed to same side of the band as the drive pulley, and the opposing nip pulleys being disposed on the opposite of the band from the other nip pulleys.

This patent application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/936,708, filed Jun. 21, 2008.

BACKGROUND OF THE INVENTION

This invention relates generally to the field of drive systems for delivering an elongated band or strap member, wherein movement of the band is required in both directions, the drive being accomplished by paired nip rollers, and whereby the nip rollers can be separated to provide a gap such that the band is not restrained when the nip rollers are separated.

Delivery of an elongated band, tape, strap or the like by running the band between a pair of cooperative nip rollers is well known. The nip rollers are rotated in opposite directions using an interconnected belt and pulley system or a chain and gear system, wherein one pulley or gear is a powered drive pulley or gear. Usually the belt will be a toothed belt of a type often referred to as a timing belt. In order to account for translating movement of at least one of the nip rollers, a spring-loaded idler is typically utilized to take up the difference in the belt length depending on whether the nip rollers are in the open (gapped) or closed (operational) disposition. This type of system is not optimal when drive torque must be supplied in both the forward and reverse directions. A typical spring loaded idler designed to take up slack in the belt during nip closure suffers an unwanted load during one of the drive directions, which causes undesired movement of the idler that results in a loss of torque. To account for this, a reversible system using a spring-loaded idler would need to have mechanical means to lock and unlock the idler depending on the drive direction.

It is an object of this invention to provide a reversible nip roll drive system that does not require a spring-loaded idler to account for belt length distances when the nip rollers are translated between the open and closed positions.

SUMMARY OF THE INVENTION

In general the invention is a reversible nip roller drive system for an apparatus having paired nip rollers for delivering an elongated band, tape, strap or the like in both a forward and reverse direction as required, with one nip roller of each set of paired nip rollers being translatable between an open and closed position. The nip rollers are mounted on or mechanically connected to nip pulleys driven by an interconnected drive belt, preferably toothed. The system comprises a drive pulley, two pairs of nip pulleys connected by shafts to the nip rollers, and a translating idler pulley. The geometry of the system is such that the drive pulley and the two nip pulleys on one side of the band are static or fixed in place, whereas the idler pulley and the opposing nip pulleys are linearly translatable as a group relative to the other pulleys, the idler pulley being positioned on the same side of the band as the drive pulley and the stationary nip pulleys, and the translating opposing nip pulleys being positioned on the opposite of the band from the stationary nip pulleys. In the open or gapped position the idler pulley and the translating nip pulleys are advanced away from the band, the stationary nip pulleys and the drive pulley in the direction perpendicular to the band. The idler and drive pulleys are positioned generally to the sides of the nip pulleys, such that the interior belt pathway between the drive pulley and one stationary nip pulley is parallel to the belt pathway between the other stationary nip pulley and the idler pulley, with the parallel belt pathway being perpendicular to the band. The spread positions of the idler and drive pulleys relative to the nip pulleys allows the system to account for the difference in belt length distances between the open and closed nip roller positions without need for a spring-loaded idler member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of the reversible nip roller drive system.

FIG. 2 is a schematic illustration of the system showing the components in the closed or drive position A and, in dashed representation, the open or gapped position B.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the drawings, the invention will now be described in detail with regard for the preferred embodiment and the best mode. In general the invention is a reversible nip roller drive system or apparatus for delivering an elongated band, tape, strap or the like in both a forward and reverse direction as required, with one nip roller of each set of paired nip rollers and an idler pulley being translatable between an open and closed position, while the other nip roller of the paired nip rollers and a drive pulley remains in a stationary or fixed position. The term pulley shall be used to encompass any driven rotational member, such as a pulley, sheave, gear or the like, and the term belt shall be used herein to encompass any looped driving member such as a belt, toothed belt, chain or the like.

The apparatus comprises the combination of a drive pulley 12, two sets or pairs of nip pulleys 13 and 14 connected to nip rollers 19 by shafts or similar mechanisms to rotate the nip rollers 19, and a linearly translating idler pulley 15. The nip pulleys 13 and 14 are driven by an interconnected drive belt 11, preferably having alternating ridges and grooves of the type commonly referred to as a timing belt, mounted on pulleys or sheaves 12, 13, 14 and 15, the pulleys having corresponding ridges and grooves to receive the belt 11 without slippage as the belt 11 moves and the pulleys 12, 13, 14 and 15 rotate in either direction. Alternatively, chains and gears could be substituted for the belt and pulleys. The belt 11 is a closed loop. One or more fixed mounting bracket members 17 are provided for the stationary drive pulley 12 and the two stationary nip pulleys 13 positioned on one side of the band 10. The translatable idler pulley 15 and the translatable opposing nip pulleys 14 are mounted onto a linearly translatable mounting bracket 16 so as to be simultaneously linearly translatable as a group relative to the drive pulley 12 and the stationary nip pulleys 13. The translatable mounting bracket 16 is moved by suitable drive means 18. The idler pulley 15 is positioned to the same side of the band 10 as the drive pulley 12, and the opposing translatable nip pulleys 14 are positioned on the opposite side of the band 10 from the stationary nip pulleys 13, the drive pulley 12 and the idler pulley 15. In the closed or drive position “A”, the sets of pulleys 13 and 14 are positioned at their smallest relative separation distance, such that the nip rollers 19 will press against the band 10 to advance it in either direction, while in the open or gapped position “B” the idler pulley 15 is advanced toward the band 10 and the translatable nip pulleys 14 are advanced away from the band 10, the stationary nip pulleys 13 and the drive pulley 12 in the direction perpendicular to the band 10 to define a gap “delta”, such that the nip rollers 19 no longer press on the band 10 and some free relative movement of the band 10 is permitted. The translatable idler pulley 15 and the stationary drive pulley 12 are disposed outwardly relative to the nip pulleys 13 and 14, the separation distance between the idler pulley 15 and the drive pulley 12 being greater than the separation distance between the two nip pulleys 13 or 14, such that the interior belt pathway between the drive pulley 12 and one stationary nip roller 13 is parallel to the interior belt pathway between the other stationary roller 13 and the idler pulley 15, with the parallel belt pathways being perpendicular to the band 10.

The spread positions of the idler pulley 15 and drive pulley 12 relative to the nip pulleys 13 and 14 allows the system to account for the difference in the overall belt pathway distances between the open and closed nip roller positions without need for a spring-loaded idler member. As the nip pulleys 13 and 14 are opened to create the gap “delta” in open position B, the belt pathway length between the translatable idler pulley 15 and the stationary nip pulley 13 shortens. Simultaneously, the belt pathway length between translatable nip pulley 14 and the stationary drive pulley 12 lengthens. When the nip pulleys 13 and 14 are closed such that the nip rollers 19 contact and move the belt 10, the belt pathway length between the translatable idler pulley 15 and the stationary nip pulley 13 increases, while the belt pathway length between translatable nip pulley 14 and the stationary drive pulley 12 shortens. Because of the geometry of the pulley positioning, the length of the total belt pathway increase is only approximately 2% of the “delta” gap distance. Since the “delta” gap distance is relatively small, for example 25 mm, the belt pathway length change is only 0.5 mm, and this amount of change is easily accommodated by inherent belt stretch.

With this structure, the reversible nip roller drive system enables torque to be delivered to the belt 10 in either direction without placing undue stress upon the idler means utilized to account for the slack occurring in the belt when the system is in the closed position A, something not possible with a spring-loaded idler mechanism.

It is contemplated that equivalents and substitutions may be obvious to those of ordinary skill in the art, and therefore the true scope and definition of the invention is to be asset forth in the following claims. 

1. A reversible nip roller drive system comprising: a stationary drive pulley; a linearly translatable idler pulley; two pairs of nip pulleys, wherein for each of said pairs one nip pulley of said pair is stationary and the other nip pulley of said pair is linearly translatable in the same direction as said idler pulley; a belt interconnecting said drive pulley, said idler pulley, said stationary nip pulleys and said translatable nip pulleys, whereby rotation of said drive pulley results in rotation of said idler pulley and said nip pulleys; wherein said drive pulley and said idler pulley are positioned on the opposite side of said nip pulleys from said translatable nip pulleys, and wherein the separation distance between said drive pulley and said idler pulley is greater than the separation distance between said pairs of nip pulleys, such that the belt pathway from said drive pulley to one of said stationary nip pulleys is parallel to the belt pathway from said idler pulley to the other of said stationary nip pulleys; wherein said idler pulley and said translatable nip pulleys are simultaneously translatable to increase and decrease the separation distance between said stationary nip pulleys and said translatable nip pulleys.
 2. The system of claim 1, further comprising a translatable mounting bracket, and wherein said translatable nip pulleys and said translatable idler pulley are mounted onto said translatable mounting bracket.
 3. The system of claim 1, said pulleys having ridges and grooves and said belt having ridges and grooves.
 4. The system of claim 1, said pulleys comprising gears and said belt comprising a chain.
 5. The system of claim 1, wherein the combination of said belt and said pulleys define a belt pathway; whereby when said separation distance between said stationary nip pulleys and said translatable nip pulleys is increased, the length of said belt pathway between said translatable idler pulley and one of said stationary nip pulleys shortens, and the length of said belt pathway between said translatable nip pulley and said stationary drive pulley lengthens; and further whereby when said separation distance between said stationary nip pulleys and said translatable nip pulleys is decreased, the length of said belt pathway between said translatable idler pulley and one of said stationary nip pulleys lengthens, and the length of said belt pathway between said translatable nip pulley and said stationary drive pulley shortens.
 6. The system of claim 5, wherein the increase in the overall length of said belt pathway under maximum separation of said stationary nip pulleys and said translatable nip pulleys is approximately two percent of the separation distance.
 7. A reversible nip roller drive system in an apparatus having nip rollers driving a band in either of two opposite directions, said system comprising: a stationary drive pulley; a linearly translatable idler pulley; two pairs of nip pulleys connected to said nip rollers, wherein for each of said pairs one nip pulley of said pair is stationary and the other nip pulley of said pair is linearly translatable in the same direction as said idler pulley, wherein said stationary nip pulleys are positioned on one side of said band and said translatable nip pulleys are positioned on the opposite side of said band; a belt interconnecting said drive pulley, said idler pulley, said stationary nip pulleys and said translatable nip pulleys, whereby rotation of said drive pulley results in rotation of said idler pulley and said nip pulleys; wherein said drive pulley and said idler pulley are positioned on the opposite side of said band from said translatable nip pulleys, and wherein the separation distance between said drive pulley and said idler pulley is greater than the separation distance between said pairs of nip pulleys, such that the belt pathway from said drive pulley to one of said stationary nip pulleys is parallel to the belt pathway from said idler pulley to the other of said stationary nip pulleys; wherein said idler pulley and said translatable nip pulleys are simultaneously translatable to increase the separation distance between said stationary nip pulleys and said translatable nip pulleys.
 8. The system of claim 7, further comprising a translatable mounting bracket, and wherein said translatable nip pulleys and said translatable idler pulley are mounted onto said translatable mounting bracket.
 9. The system of claim 7, said pulleys having ridges and grooves and said belt having ridges and grooves.
 10. The system of claim 7, said pulleys comprising gears and said belt comprising a chain.
 11. The system of claim 7, wherein said translatable idler pulley and said translatable nip pulleys translate in a direction perpendicular to said band.
 12. The system of claim 7, wherein the combination of said belt and said pulleys define a belt pathway; whereby when said separation distance between said stationary nip pulleys and said translatable nip pulleys is increased, the length of said belt pathway between said translatable idler pulley and one of said stationary nip pulleys shortens, and the length of said belt pathway between said translatable nip pulley and said stationary drive pulley lengthens; and further whereby when said separation distance between said stationary nip pulleys and said translatable nip pulleys is decreased, the length of said belt pathway between said translatable idler pulley and one of said stationary nip pulleys lengthens, and the length of said belt pathway between said translatable nip pulley and said stationary drive pulley shortens.
 13. The system of claim 12, wherein the increase in the overall length of said belt pathway under maximum separation of said stationary nip pulleys and said translatable nip pulleys is approximately two percent of the separation distance. 